Preparation of bean dreg derived N-doped activated carbon with high adsorption for Cr(VI)

In this study, N-doped activated carbon BDC-STM30-10.0HT was prepared from bean dreg by using steam activation and heat treated at 1000 degrees C under helium gas flow for the removal of Cr(VI). The properties of the prepared carbon catalysts were characterized by CHN elemental analyzer, SEM, N-2 adsorption and XPS techniques, and the obtained bean dreg activated carbon BDC-STM30-10.0HT had a high specific surface area (1004 m(2)/g) and high quaternary nitrogen content (1.11 %). Activated carbon with different specific surface areas was prepared by changing the temperature during high temperature treatment and the order of high temperature treatment and steam activation. The results of batch adsorption experiments showed that the Cr(VI) adsorption capacity of activated carbon was positively correlated with the specific surface area, but it does not only depend on the specific surface area, but also quaternary nitrogen. The adsorption equilibrium data were well described by the Langmuir model, and BDC-STM30-10.0HT had excellent adsorption capacity for Cr(VI) (3.30 mmol/g). BDC-STM30-10.0HT showed superior recyclability, and after five times regenerations, the adsorption capacity of BDC-STM30-10.0HT still had 54 % of the initial adsorption capacity.